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Thread: AR10/.308 AR Build knowledge thread.

  1. #101
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    Quote Originally Posted by LRRPF52 View Post
    You can do either, but I personally would go RLGS 18" with a .308 Win. Look at one of the most reliable configurations on the market, the SR25 carbines.

    They use 16" pipes with RLGS, but they also know what they're doing when it comes to the gas system.

    Your ammunition, port diameter, and how well the gas is sealed will determine whether or not you need adjustable gas.


    Awesome, thank you.

  2. #102
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    Quote Originally Posted by LRRPF52 View Post
    That is the 1st LR-308 "lo-pro" upper, commonly referred to as the "high profile" receiver height. DPMS introduced it with the LR-308. Then came the AP4, and now the GII.
    Maybe you're forgetting that they "revised" one of their rail heights (3/16" to 1/8")?

    Straight from DPMS (circa 2010):
    The LR308 Platform has two heights, the A3 and Lo-Pro Raised Rail. The A3 was changed recently to better accommodate our other components. I guess in reality, with the number sold before the change, there are now 3 heights.

    To find out if you have a newer model or older run, the easiest way to measure is with a caliper from the bottom surface that mates to the lower to the top of the rail. The new versions measure 2.003 and the old versions are 2.063.
    Add the new GII and that's four different heights.
    Last edited by Plasman; 11-24-14 at 00:14.

  3. #103
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    Quote Originally Posted by Plasman View Post
    Maybe you're forgetting that they "revised" one of their rail heights (3/16" to 1/8")?

    Straight from DPMS (circa 2010):


    Add the new GII and that's four different heights.
    And here I was thinking I had somewhat of a handle on the variances....

    What else has slipped by me over the decades of trying to keep track of this mess? And people say that the "DPMS pattern" should just be the standard, so we can all move on and make "everything the same".

    It becomes more and more of a minefield once you step into it. I'll continue with my plan to sacrifice a complete rifle for a donor action.

  4. #104
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    Quote Originally Posted by Plasman View Post
    Added the new GII and that's four different heights.
    LOL...what does DPMS pattern mean these days!?!?

    Low profile
    high profile
    Gen
    Gen ii?
    Last edited by kpinole; 11-26-14 at 10:38.

  5. #105
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    Quote Originally Posted by kpinole View Post
    LOL...what does DPMS pattern mean these days!?!?

    Low profile
    high profile
    Gen
    Gen ii?
    It refers to the LR308 receiver cut (since the most common question here is "will this upper receiver mate with this other lower receiver?"). The top rail height is then added as a modifier after such as "DPMS high profile upper receiver."

    G2 is it's own thing =P.

  6. #106
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    I really like the maten I just built. Yes the rail is proprietary but the whole combo is light and I really like how easy the rail comes on and off if I want to get at the gas system. Also the rail does not touch the barrel nut.



  7. #107
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    Looking at barrel-nut options and have a few questions:

    Go with 'standard' 308 barrel nut and delta-ring: is there a difference between AR308 (dpms) and AR10?
    Then looking at (standard) barrel nut only (regardless of rail-height or style) since the barrel nut is a different size, the standard AR15 'delta ring -package' wont fit either so I'll need a 308 weld spring delta ring etc. - correct?
    If so, whatever rail one chooses has to fit that as well, unless one goes with a proprietary barrel-nut/rail-system.
    Meaning standard AR rails are not an option. Again - I am not looking at rail-height, barrel attachment point only.
    Thanks.
    Last edited by polydeuces; 12-02-14 at 19:56.
    Per Ardua ad Astra.
    STS - gone but not forgotten.

  8. #108
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    Quote Originally Posted by polydeuces View Post
    Looking at barrel-nut options and have a few questions:

    Go with 'standard' 308 barrel nut and delta-ring: is there a difference between AR308 (dpms) and AR10?
    Then looking at (standard) barrel nut only (regardless of rail-height or style) since the barrel nut is a different size, the standard AR15 'delta ring -package' wont fit either so I'll need a 308 weld spring delta ring etc. - correct?
    If so, whatever rail one chooses has to fit that as well, unless one goes with a proprietary barrel-nut/rail-system.
    Meaning standard AR rails are not an option. Again - I am not looking at rail-height, barrel attachment point only.
    Thanks.
    The LR-308/SR-25 barrel nut thread pitch is different than the AR-10's. They're not interchangeable.

    AR-15 handguards and rails aren't compatible with LR-308 or AR-10 barrel nuts.

    The GII barrel nut outer diameter however, is the same as the AR-15 milspec barrel nut and will accept some AR-15 handguards. The upper receiver rail height from the center of the bore is also the same as an AR-15's. GII barrel nuts have a different thread pitch compared to the LR-308 and AR-10.

  9. #109
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    So there goes my budget....should've known.

    Regarding RE/Spring/Buffer set up:
    From my experience this is where the functioning stands or falls - this and gas-port diameter.

    Going by earlier posts the AR10 style is most reliable, so my thinking is going with an AR10 RE and spring, use a standard AR buffer with the appropriate weight. Just went ahead and placed an order for this.

    Run this with an adjustable gas-block I can really tweak it between that and buffer weight.
    Anything wrong with that thinking? - I am assuming the threads etc on AR10 and AR308/DPMS/SR25 (...sigh.....) are identical...I hope....please...?

    (Yeah - I am in deep now. Not quitting either till this f#@*er is built and running like a champ. If it's the last thing I do.)
    Per Ardua ad Astra.
    STS - gone but not forgotten.

  10. #110
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    I'll throw a few things out there to add to the mix.

    PWS receiver sets apparently are sold separately and are supposed to be DPMS low pro.

    SLR Rifleworks is making a boat load of DPMS high profile rails in Keymod and Magpul M-LOK design. They are also gradually adding a few DPMS low pro rails.


    A company called Matrix Aerospace makes the receiver sets Ruger uses on the SR-762 which are based on the Armalite AR10A (pmag) pattern. Last I contacted them, they supplied me with a price sheet for the receiver sets and various parts. They told me standard Armalite parts will also work.

    I wasn't far away from buying a set and building my own until I saw the cost of Armalite BCGs compared to DPMS pattern. Also it seems that manufacturers and/or suppliers (like Rainier) are getting away from the Armalite barrel extension in favor of DPMS pattern. Armalite doesn't make any reasonably priced barrels in a desirable design and that would fit my accuracy expectations. A few custom barrel makers I've spoken to would roll me a match SS barrel substituting an Armalite barrel extension and would headspace if I sent them a bolt. I would prefer a common and more mass produced barrel.

    So I found the Mega nitrided (not sure if that really means QPQ or melonite) SS barrels and was in search for a well priced and reliable BCG and forged receiver set. I just gave up at that point and bought a complete rifle.

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